Apparatus for accomplishing sonic fusion welding and the like involving variable impedance load factors

ABSTRACT

PARTS TO BE WELDED TOGETHER ARE SUPPRTED WITH THE SURFACES TO BE JOINED IN CONTACT WITH ONE ANOTHER. A RESONATOR MEMBER IS COUPLED TO AT LEAST ONE OF THE PARTS AND AN ORBITING MASS OSCILLATOR IS CONNECTED TO SAID RESONATOR MEMBER. THE ORBITING MASS OSCILLATOR IS DRIVEN AT A FREQUENCY SUCH AS TO CAUSE RESONANT ELASTIC VIBRATION OF THE ASSOCIATED RESONATOR MEMBER SLIGHTLY BELOW THE PEAK RESONANT FREQUENCY. THE SONIC ENERGY IS TRASMITTED TO THE SURFACES TO BE JOINED, GENERATING HEAT AT SUCH SURFACES THEREBY FUSSING THE PARTS TOGETHER.

Nov. 14, 1972 A. s. BODINE 3,702,674

APPARATUS FOR ACCOMPLISHING SONIC FUSION WELDING AND THE LIKE INVOLVINGVARIABLE IMPEDANCE LOAD FACTORS Original Filed March 24, 1966 4Sheets-Sheet 1 Nov. 14, .1972 A. s. BODINE ,7

APPARATUS FOR ACCOMPLISHING SONIC FUSION WELDING AND THE LIKE INVOLVINGVARIABLE IMPEDANCE LOAD FACTORS Original Filed March 24, 1966 4Sheets-Sheet 2 3 a 5% m; w: 3%

NOV. 14, 1972 BQDINE APPARATUS FOR ACCOMPLISHING SONIC FUSION WELDINGTHE LIKE INVOLVING VARIABLE IMPEDANCE LOAD FACTORS Original Filed March24, 1966 A. APPARATUS FOR ACCOMPLI Nov. 14, 1972 G. BODINE 3,7

SHING SONIC FUSION WELDING AND THE LIKE INVOLVING VARIABLE IMPEDANCELOAD FACTORS Original Filed March 24, 1966 4 Sheets-Sheet 4 rawy.

mg m 006 MNIMIIINN Mud.

United States Patent US. Cl. 228-1 6 Claims ABSTRACT OF THE DlSCLOSUREParts to be welded together are supported with the surfaces to be joinedin contact with one another. A resonator member is coupled to at leastone of the parts and an orbiting mass oscillator is connected to saidresonator member. The orbiting mass oscillator is driven at a frequencysuch as to cause resonant elastic vibration of the associated resonatormember slightly below the peak resonant frequency. The sonic energy istransmitted to the surfaces to be joined, generating heat at suchsurfaces thereby fusing the parts together.

This application is a division of my application Ser. No. 804,798, filedMar. 6, 1969, which is a division of my application Ser. No. 537,163,filed Mar. 24, 1966, now Pat. No. 3,439,409.

This invention is directed to apparatus for application of sonicvibratory welding for making certain types of weld joints.

A Welding process called friction welding is now known, wherein twoparts to be welded are rotated together under pressure until the heatgenerated thereby causes a softening of the metal. The rotation is thenstopped and the parts forged together, generally with application ofadditional pressure. The process presents the problem of stopping therotation precisely before the softened metal is disrupted, and theprocess is inapplicable for various reasons in many situations.

'Sonic, non-fusion welding, particularly in the ultrasonic range, hasbeen applied to two thin work pieces in contact with one another, forexample, by transmitting lateral vibrations to one of the pieces along acoupling stem froma magnetostriction transducer, or the equivalent. Thelaterally vibratory coupling stem engages against an outside surface ofthe work piece to which it is coupled, and vibrates laterally in theplane of this outside surface. Apparently, through frictional vibrationsof the coupling stem against this outside surface of the work piece, avibratory shear stress is established in the piece, and withthesimultaneous application of pressure, a sort of crystal interlockwith the other piece can be produced. The temperature is below thefusion temperature, and this is therefore not a case of fusion welding,but essentially a cold-weld process.

The present invention is concerned with a situation wherein at least oneof the parts being welded is of an elongated nature, like a piece ofpipe, and wherein torsional elastic vibrations are engendered within thepart being welded. These elastic vibrations cause the part being weldedto experience elastic hysteresis effects, which cause internal heatingwithin the part. This internal heating within the part is a verysignificant factor in this invention because the elongated part issubjected to an actual pattern of elastic vibrations. This internalhysteresis heating of the part is so significant because it ends to3,702,674 Patented Nov. 14, 1972 avoid the extraction of heat by thepart from the localized region where the sonic friction weld is takingplace at the end of the part. The elongated parts otherwise would tendto extract heat from the weld region, and thereby interfere with theweld action. The elongated shape of the part involves a considerableamount of surface area along the side walls, which aggravates thedissipation of heat from the weld region. The above mentioned benefitsaccrue from the invention disclosed herein, where an elongated membersuch as a pipe or the like is welded to another member, which othermember can also be an elongated member.

The sonic welding of the present invention is of a novel vibratory,friction-fusion type, involving transmission of sonic vibratory energythrough or into a work piece to be welded, in a manner to causevibration of the work piece relative to another work piece which is tobe welded to the first and which is being held against the latter. Useof the word sonic should not be under stood as implying limitation tothe subjective limits of audibility, but includes frequencies both aboveand below the audible range. It refers instead to vibrations in thenature of sound waves, often characteristically, but not necessarily,within the audible spectrum. The metal of the two work pieces is heatedand softened by the ensuing vibratory friction, and welds by fusion. Asthe material fuses, and the weld then sets up, certain substantialchanges take place in acoustic impedance at the weld, and a principalfeature of the present invention is that these changes in impedance areacoustically accommodated to advantage in the practice of the invention,as will appear hereinafter.

It is a characteristic of the practice of the present invention thatthere be employed a resonant acoustic circuit, including an oscillatoror vibration generator, and a tuned vibration transmitter, or resonator,acoustically coupled and mechanically connected to the vibrated workpiece. The vibrated work piece, as well as the mating work piece towhich the former is to be welded, are part of the resonant acousticcircuit. The tuned vibration transmitter may be a circuit element inaddition to the vibrated work piece, or may comprise a part of, or bethe entirety of, the vibrated work piece. In most cases, and in thepreferred practice, the transmitter or resonator part of the circuit ispredominantly of a distributed constant character, with elements of massand elasticity distributed throughout it, so as to vibrate at resonancein a resonant standing wave pattern. The circuit may often containlumped masses or compliances, however, which may substantially modifythe standing wave pattern, or give it a complex character. It is alsopossible to practice the broad invention with a discrete acousticcircuit involving substantially only lumped constants, e.g., a vibrationgenerator, and a resonator and load combination comprised simply oflumped compliance and mass elements.

The present invention is reliant for success upon certain basicprinciples of acoustics of considerable obscurity. An acoustic systemsuch as is utilized in the practice of the invention amounts to adiscrete resonant acoustic circuit, inclusive of a vibration generator,a resonant, elastic, acoustic energy transmitter, or elastic resonator,and a load, which is the wor The generator and transmitter or resonatorcomponents constitute an acoustic tool; the work constitutes the varyingimpedance load which receives sonic energy from the acoustic tool;

and the whole comprises a discrete acoustic circuit. These circuitelements and their interrelationships, in turn, often involveconsiderations of impedance, frequency, wavelength, resonance, phaseangle, power factor, and the like, and such parameters must be orderedso that the work acts as a working part of this acoustic circuit, andthe result desired follows from energization and operation of thecircuit. The ability of the invention to carry out assigned tasksusefully and effectively depends of course upon the operationaleffectiveness of the circuit, and therefore upon how well the circuithas been contrived to carry out the work process in hand.

The fundamental system of the present invention depends upon use of acertain orbital-mass type of vibration generator in the acousticresonant circuit mentioned above. vIt has been mentioned earlier thatthe site of the weld undergoes certain changes in impedance during theprocess, and these have certain effects such as on resonance vibrationfrequency and power factor. The orbitalmass vibration generator uniquelyaccommodates these changes in the course of the welding process, as willbe stressed hereinafter.

The orbital-mass generator may take any of various mechanical forms, ofwhich the simplest is a mass eccentrically mounted on a shaft turning ina bearing, so that the mass generates a centrifugal force which isreactively opposed by the bearing. The bearing is on a support frame, inresponse to the centrifugal force so generated and applied, exerts aperiodic inertial force on whatever may support it or be coupledthereto. Some improved forms of onbital-mass generator or oscillator aredisclosed in my Pats. Nos. 2,960,314 and 3,217,551. In these patents aredisclosed orbital-mass oscillators comprising a cylindrical mass rollingaround the inside of a bearing race ring, and a ring-shaped massspinning on a bearing pin. In some cases, the generator may be driven byan electrical motor such as an induction motor or, where increased speedresponsiveness to load is desired, by a series motor. In others, as inthe case of rollers or rings, the drive may be by an air or other fluidjet directed against the roller or ring. Thus, in many cases, a sliptypedrive is used. In all cases, there is an orbiting mass comprised of aweight driven so as to travel around a closed circular path, which pathis determined by a circular bearing forcibly constraining the weight totravel in this curved path. The bearing then experiences a powerfulrotating reaction force caused by the weight moving along its circularpath, which force is periodic in nature because each point spaced aroundthe bearing is periodically subjected to this force. Together with itssupport frame, the bearing is thus a reactive coupling output device.

Also, in all cases, the bearing has a support frame, as aforesaid,adapted for making the actual coupling to the system to be vibrated. Themass of the bearing and support frame may be very considerable inrelation to that of the orbiting mass. The momentum imparted to thisconsiderable mass must be equal to that of the small orbital mass, andsince the velocity of the small orbital mass is quite high, the motionof this considerable mass is thus relatively low. I therefore have theadvantage of a large mass moving periodically with great force ormomentum, but through small displacement distance at relatively lowvelocity. This represents a condition of relatively high impedance(defined hereinafter) in the support frame, ie in the generator outputcoupling element, such as is uniquely suited to the circuit requirementsof the present invention.

Such a vibration generator may be arranged and utilized so as to deliverfrom the generator support frame, or coupling means, a continuouslyrotating force vector. In the more usual case, however, the desired oruseful output is an alternating force doing Work in reverse directionsalong a given direction line, and such a force, and other very importantadvantages to be mentioned, are obtained by combining with theorbital-mass generator a suitable resonator system, such as a relativelymassive elastic resonator bar. The bar is, for example, attached at oneend to the support frame of the generator, so that it has impressedthereon periodic output impulses from the generator. The bar ma'y then,for example, have such a length in relation to the frequency orperiodicity of the generator (circuits per second of the orbital mass)as to vibrate longitudinally in a halfwave length or fundamentalresonant standing wave pattern. The end of the bar attached to thegenerator support frame, together with the latter, then vibratelongitudinally of the bar; the opposite end of the bar, which may be thework performing end, vibrates longitudinally in opposite phase to thefirst mentioned end; and a mid region of the bar has minimized vibrationamplitude. The latter region is the location of a node or pseudonode ofthe standing wave, while the moving ends are at antinodes of the wave.The bar will be seen to alternately elastically elongate and contractand by this motion may do Work. This standing wave performance is aresonant phenomenon, and in this case, assuming a uniform bar, andneglecting lumped constant effects of the masses at the two ends of thebar, occurs when where f is the fundamental resonant frequency, s isequal to the velocity of sound in the bar, and h is the length of thebar. At resonance, the mass and compliance reactances of the vibratorysystem are equal and cancel one another, the impedance to vibration ofthe masses of the system is thereby reduced to that owing to friction(actual work done), and vibration amplitude in the bar is reso nantlymagnified by a large factor. In effect, the blocking impedance of themasses along the direction line of the bar has been very greatlyreduced, generator output force consumed by this impedance along thisdirection line is correspondingly diminished, and large vibratory motionalong the direction line of the bar is attained.

In this resonant performance, the large necessary vibratory masses ofthe system are tuned out and consume none of the output force from theorbital-mass generator. They are moved by elastic restoration forcesexerted by the deformed compliances, which are in turn elasticallydeformed, of course, in decelerating the masses. Thus the massiveelastic system vibrates with no consumption of force save for that lostin friction and in doing useful work.

A further considerable advantage in the system is that the masses willthen vibrate at substantial amplitude (exhibit large vibrationaldisplacement), and become a powerful acoustic flywheel, storingconsiderable energy. The masses become an advantage. The system exhibitsresonant magnification of motion. This gives a system which can build upto high vibratory power level; and the energy storage flywheel effectalso gives the ability to ride over irregularities presented by the workload.

From the foregoing it will be appreciated that an orbiting mass, such asone confined to traveling around a circular path, delivers its reactionagainst this confinement as a reactive centrifugal force whichinherently rotates so as to be a force oriented successively in alldirections in a plane. On the other hand, as has been shown, theresonating bar, or equivalent, can, for example, be a longitudinallyelastically vibratory bar. Such resonant motion is thus typicallyvibration back and forth along a line or path. Since such resonance,however, eliminates the blocking effect of the masses only along thisline or path, the vibratory amplitude will be of substantial magnitudeonly along this same line or path, even though the oscillator isdelivering force in an infinite number of directions radiating aroundthe focal center of the mass orbit. The above described natural blockingeffect of the masses thus prevents the vibration from being substantial,except in the path direction or directions along which the phenomenon ofresonance has eliminated the blocking mass effect as described. Theperformance of the orbitalmass oscillator, in combination with theresonance exerted thereby, and which I term orbit-resonance, can thuspolarize the resulting vibration from the oribiting mass, and givesstability of vibratory motion along this line of orientation. Thevibration stroke can thus be confined along a predetermined path.

Another very important property of the present system is a uniquefrequency stability. An orbiting mass vibration generator by itself cantend to change its frequency from time to time. However, in theorbit-resonance system, this orbiting mass is acoustically coupled to aresonant vibratory system, with dimensional proportions adjusted so thatthe orbiting mass is very conscious, so to speak, of the impedance ofthe resonant system. Within the resonant frequency range, and especiallyin the preferred operating region on the low side of the resonance peak,where resonant magnification exhibits sharply increasing amplitude inresponse to increasing frequency, the orbiting-mass oscillatorautomatically tends to lock in and hold to a stable frequency condition.The explanation is as follows: A slight increase in frequency, resultingfrom any cause, produces an increase in vibration velocity andamplitude. This results from the reactive part of the impedance havingbeen thereby diminished. The phase angle of the orbital mass is thusimproved, so more work can be done if more drive effort is supplied.Thus, more drive torque is required of the orbiting-mass oscillator,and, in turn, more drive effort from its drive source or prime mover.Thus, the vibratory system, operating near resonance, feeds back ademand for additional drive effort. Using a drive source whose driveeffort on the oscillator remains constant, or whose output isinsuflicient to develop the increased drive torque demanded at theincreased frequency, or using as a source a prime mover which isinversely speed-responsive to load (e.g., an induction motor, or forgreater responsiveness, a series motor), the system responds by actuallyreducing the drive speed of the oscillator in the face of this increasein demand for drive torque. Thus the initially assumed slight increasein frequency is corrected. The system similarly responds to a slightdecrease in frequency by moving further from resonance, and through aprocess which will now be evident, produces increased speed at theorbiting-mass vibration generator such as to correct the assumed slightdecrease in frequency. The system thus automatically holds a determinedfrequency. Bearing in mind the impedance equation F VZ, where F is driveforce exerted by the oscillator on the vibratory system, and V is thevelocity of vibration, an increase in frequency toward the resonancepeak must be accompanied by increase in V and in the total energy of thesystem, and the force factor F must be sufficient that this will be donenotwithstanding a decrease in the reactive component of the impedance Zas resonance is approached. The force F must be increased to reach orsustain the new conditions, and thus the above mentioned demand forincreased torque takes place. This increase in torque is not supplied.Therefore, the frequency reduces following, or in response to, theincrease which first took place. The system thus has inherent frequencystability.

The combined system of an orbital-mass vibration generator and resonatorhas a unique performance which is exhibited in the form of a greatereffectiveness and particularly greater persistence in sustained sonicaction as the work process goes through successive phases involvingchanges of working conditions. The oribiting mass generator in thiscombination is able to sustain its development of power for the load asthe sonic energy absorbing environment changes with the variations insonic energy absorption by the load. It does this by automaticallychanging its phase angle, and therefore its power factor, with thesechanges in the resistive impedance of the load.

This can be explained as follows: Consider the orbitalrnass oscillatorused in this invention, say of the type involving a roller masstraveling in a circular path around the inside of a cylindrical bearing,and assume this bearing to be fixed to a free end of an elastic bar, theaxis of the bearing being perpendicular to the length axis of the bar.Assume further that the roller mass is driven around the bearing at afrequency of s/2h cycles per second, where s is the velocity of sound inthe bar and h is the length of the bar, so that the bar is driven by thecyclic output force exerted by the bearin g to undergo halfwavelengthstanding wave vibration. The bar then alternately elastically elongatesand contracts, at the cyclic frequency of the roller mass. Thelongitudinal velocity of the driven end of the bar, and also the forceexerted by the bearing on the bar, can then be plotted as sinusoidalwaves. With no net work done on or through the bar, the force wave thenlags the velocity wave by The phase angle of the roller in its race issuch that at this time it moves longitudinally of the bar in step withthe oscillator end of the bar. This is a condition of 90 phase angle, apower factor of zero, and zero net work done. Assume now that thevibrating bar is subjected to substantial friction. The velocity waveloses amplitude, and the roller mass automatically undergoes an angularshift in position within its race so as to bring the sinusoidal forcewave more into phase with the velocity wave. The phase angle is thusreduced, and power factor increased the necessary amount for thegenerator to develop and supply the energy consumption required by thefriction now encountered. correspondingly, if the friction were large tostart, and subsequently diminished, the phase angle would be small tostart, and would subsequently go towards or to substantially 90 withprogressive elimination of friction.

Also, if the load on the orbital-mass oscillatorresonator combinationshould vary in mass reactance, or elastic compliance reactance, duringoperation, the frequency and phase angle of the oscillator will shift toaccommodate these changes. A change in reactance of a vibratory systemcan be accomplished, for example, if during vibratory operation, a parthaving mass is welded to a vibrating part. Such a change in reactanceresults in a change in impedance, phase angle, and resonance frequency.If the prime mover is one which has slip, or is speed-responsive totorque, there is a resulting automatic feedback of torque to the primemover which drives the orbiting-mass oscillator such as to re-establishstable op eration at a new resonant frequency, and with adjusted phaseangle and power factor which automatically accommodate the addedreactance and any remaining energy consuming load. Any changes inmagnitude of either or both the friction or energy consuming part of theload and the reactive part of the load are thus automaticallyaccommodated by the invention so that the oscillator sustains itsdevelopment and transmission of power into the load throughout all suchchanges.

To accomplish these performances the resonant system must besufficiently large relative to the resistive impedance so as to exhibitresonant magnification. Moreover, the orbital-mass generator must havesufficient output force and impedance so as to accomplish such resonantmagnification, even with the resistive load; and this generator outputmust also be large enough to cause the stabilizing torque load on thegenerator drive. However, the generator output and input should not beso high as to cause a power flow which overrides the resonant feedbackphenomenon above described. This resonance phenomenon could beundesirably buried if it is simply caught between a very powerfulgenerator and a large resistive load.

The invention is further disclosed hereinafter in a number of practicalapplications, all of which involve the broad principles of theinvention, but each of which involves specific unique features ofinvention. These will be disclosed and stressed in connection with thedescriptions of illustrative apparatus for carrying out the severalpractical applications referred to just above.

Before proceeding with the detailed descriptions of the invention,however, there will be presented a discussion of certain principles ofsonics necessary to an understanding of the invention, some of which aregenerally familiar to those skilled in the art, but a number of whichare not.

SONIC DISCUSSION Certain acoustic phenomena disclosed in the foregoingand hereinafter, are, generally speaking, outside the experience ofthose skilled in the acoustics art. To aid in a full understanding ofthese phenomena by those skilled in the acoustics art, and by others,the following general discussion, including definition of terms, isdeemed to be of importance.

By the expression sonic vibration I mean elastic vibrations, i.e. cyclicelastic deformations, such as longitudinal, lateral, gyratory,torsional, etc., produced in an elastic structure, or which travelthrough a medium with a characteristic velocity of propagation, andwhich are often at resonance in the structure, or are involved withtraveling or standing waves. If these vibrations travel longitudinally,or create a longitudinal wave pattern in a medium or structure havinguniformly distributed constants of elasticity and mass, this is thesimplest form of sound wave transmission. Regardless of the vibratoryfrequency of such sound wave transmission, the same mathematicalformulas apply, and the science is called sonics irrespective of audiblelimits. In addition to purely distributed constant systems, there can beelastically vibratory (sonic) systems wherein the essential feature ofmass appears wholly or in part, as a localized influence or parameter,known as a lumped constant; and another such lumped constant can be alocalized or concentrated elastically deformable element, affording alocal effect referred to variously as elasticity, modulus, modulus ofelasticity, stiffness, stiffness modulus, or compliance, which is thereciprocal of the stiffness modulus. Fortunately, these constants, whenfunctioning in an elastically vibratory system such as mine, havecooperating and mutual influencing effects like equivalent factors inalternating-current electrical systems. In fact, in both distributed andlumped constant systems, mass is mathematically equivalent toinductances (a coil); elastic compliance is mathematically equivalent tocapacitance (a condenser); and friction or other pure energy dissipationis mathematically equivalent to resistance (a resistor).

Because of these equivalents, my elastic vibratory systems with theirmass and stiffness and energy consumption, and their sonic energytransmission properties, once they have been conceived of as acousticcircuits, can be viewed as equivalent electrical circuits, where thefunctions can be expressed, considered, changed and quantitativelyanalyzed by using well proven electric formulas.

It is important to recognize that the transmission of sonic energy intothe interface or work area between two parts to be moved against oneanother requires the above mentioned elastic vibration phenomena inorder to accomplish the benefits of my invention. There have been otherproposals involving exclusively simple bodily vibration of some part.However, these latter do not result in the benefits of my sonic orelastically vibratory action.

Since sonic or elastic vibration results in the mass and elasticcompliance elements of the system taking on these special propertiesakin to the parameters of inductance and capacitance inalternating-current phenomena, wholly new performances can be made totake place in the mechanical arts. The concept of acoustic impedancebecomes of paramount importance in understanding performances. Hereimpedance is the ratio of cyclic force or pressure acting in the mediato resulting cyclic velocity or motion, just like the ratio of voltageto current. In this sonic adaption impedance is also equal to mediadensity times the speed of propagation of the elastic vibration.

Impedance is important to the accomplishment of desired ends, such aswhere there is an interface. A sonic vibration transmitted across aninterface between two media or two structures can experience somereflection, depending upon differences of impedance. This can be availedof, if desired, to cause large relative motion at the interface.

Impedance is also important to consider if optimized energization of asystem is desired. If the impedances are adjusted to be matchedsomewhat, energy transmission is made very effective.

Sonic energy at fairly high frequency can have energy effects onmolecular or crystalline systems. Also, these fairly high frequenciescan result in very high periodic acceleration values, typically of theorder of hundreds or thousands of times the acceleration of gravity.This is because mathematically acceleration varies with the square offrequency. Accordingly, by taking advantage of this square function, Ican accomplish very high forces with my sonic systems.

An additional important feature of these sonic circuits is the fact thatthey can be made very active, so as to handle substantial power, byproviding a high Q factor. Here this factor Q is the ratio of energystored to energy dissipated per cycle. In other words, with a high Qfactor, the sonic system can store a high level of sonic energy, towhich a constant input and output of energy is respec tively added andsubtracted. Circuit-wise, this Q factor is numerically the ratio ofinductive reactance to resistance. Moreover, a high Q system isdynamically active, giving considerably cyclic motion Where such motionis needed.

Certain definitions should now be given:

Impedance, in an elastically vibratory system, is, mathematically, thecomplex quotient of applied alternating force and linear velocity. It isanalogous to electrical impedance. The concise mathematical expressionfor this impedance is where M is vibratory mass, C is elastic compliance(the reciprocal of stiffness, or of modulus of elasticity) and f is thevibration frequency.

Resistance is the real part R of the impedance, and represents energydissipation, as by friction.

Reactance is the imaginary part of the impedance, and is the differenceof mass reactance and compliance reactance.

Mass reactance is the positive imaginary part of the impedance, given byHM. It is analogous to electrical inductive reactance, just as mass isanalogous to inductance.

Elastic compliance reactance is the negative imaginary part ofimpedance, given by 1/21rfC. Elastic compliance reactance is analogousto electrical capacitative reactance, just as compliance is analogous tocapacitance.

Resonance in the vibratory circuit is obtained at the operatingfrequency at which the reactance (the algebraic sum of mass andcompliance reactances) becomes zero. Vibration amplitude is limitedunder this condition to resistance alone, and is maximized. The inertiaof the mass elements necessary to be vibrated does not under thiscondition consume any of the driving force.

A valuable feature of my sonic circuit is the provision of enough extraelastic compliance reactance so that the mass or inertia of variousnecessary bodies in the system to depart so far from resonance that alarge proportion of the driving force is consumed and wasted invibrating this mass. For example, a mechanical oscillator or vibrationgenerator of the type normally used in my inventions always has a body,or carrying structure, for containing the cyclic force generating means.This supporting structure, even when minimal, still has mass, orinertia. This inertia could be a force-wasting detriment, acting as ablocking impedance using up part of the periodic force output just toaccelerate and decelerate this supporting structure. However, by use ofelastically vibratory structure in the system, the effect of this mass,or the mass reactance resulting therefrom, is counteracted at thefrequency for resonance; and when a resonant acoustic circuit is thusused, with adequate capacitance (elastic compliance reactance), theseblocking impedances are tuned out of existence, at resonance, and theperiodic force generating means can thus deliver its full impulse to thework, which is the resistive component of the impedance.

Sometimes it is especially beneficial to couple the sonic oscillator orvibration generator at a low-impedance (highvelocity vibration) region,for optimum power input, and then have high impedance (high-forcevibration) at the work point. The sonic circuit is then functioningadditionally as a transformer, or acoustic lever, to optimize theeffectiveness of both the oscillator region and the work deliveringregion.

For very high-impedance systems having high Q at high frequency, Isometimes prefer that the resonant elastic system be a bar of solidmaterial such as steel. For lower frequency or lower impedance,especially where large amplitude vibration is desired, I use a fluidresonator. One highly desirable specie of my invention employs, as thesource of sonic power, a sonic resonant system comprising an elasticresonator member in combination with an orbiting mass oscillator orvibration generator, as above mentioned. This combination has manyunique and desirable features. For example, this orbiting massoscillator has the ability to adjust its input power and phase to theresonant system so as to accommodate changes in the Work load, includingchanges in either or both the reactive impedance and the resistiveimpedance. This is a very desirable feature in that the oscillator hangson to the load even as the load changes.

It is important to note that this unique advantage of the orbiting massvibration generator accrues from the use thereof in the acousticresonant circuit, so as to comprise, with the work or load, a completeacoustic system or circuit. In other words, the orbiting mass vibrationgenerator is matched up tothe resonant part of its system, and thecombined system is matched up to the acoustic load, or the job to beaccomplished. One manifestation of this proper matching is acharacteristic whereby the orbiting mass oscillator tends to lock in tothe resonant frequency of the resonant part of the system.

As will be noted, this invention involves the application of sonic powerwhich brings forth some special problems unique to this invention, whichproblems are primarily a matter of delivering effective sonic energy tothe particular work process involved in this invention. The workprocess, as explained elsewhere herein, presents a special combinationof resistive and reactive impedances. These circuit values must beproperly met in order that the invention be practiced effectively.

The invention will be further understood from the following detaileddescription of a generic representation and a number of specificillustrative embodiments thereof, reference for this purpose being hadto the accompanying drawings, in which:

FIG. 1 is a diagrammatic view of an acoustic circuit illustrative of theinvention;

FIG. 2 is a side elevational view, with some parts shown in verticalmedial section, of a sonic machine for fusion welding of the abuttingends of two sections of pipe;

FIG. 3 is a transverse section taken as indicated by line 3-3 of FIG. 9;

FIG. 4 is a view similar to FIG. 2, but showing the parts in a differentposition;

FIG. 5 is a section taken on line 44 of FIG. 2;

FIG. 6 is a section taken on line 6-6 of FIG. 9;

FIG. 7 is a diagrammatic view showing the pipes being welded in theapparatus of FIGS. 2-6 and showing certain standing wave diagramsdemonstrating the operation of the machine;

FIG. 8 is a diagrammatic view illustrative of the phasing of a pair ofvibration generators as used in the system of FIGS. 2-6;

FIG. 9 is a side elevational view, with parts broken away in medialsection, showing an illustrative app1ication of the invention to thewelding of a pair of universals joints to opposite ends of a tubularshaft;

FIG. 10 is a transverse section taken on line 1010 of FIG. 9;

FIG. 11 is a detail section taken on line 11-11 of FIG. 9;

FIG. 12 is a diagrammatic view of the apparatus of FIG. 9 showing also astanding Wave as set up in the hollow shaft in the operation of thesystem;

FIG. 13 is a side elevational view, with parts in vertical medialsection, showing an application of the invention to the fusion weldingof a pin or shaft to a surface area on a large body; and

FIG. 14 is a detail section taken on line 14--14 of FIG. 13.

Reference is first directed to FIG. 1, illustrative schematically of thebasic acoustic system of the invention, and of all the subsequentlydescribed species thereof. An oscillator or elastic vibration generator,of the orbitalmass type, as described hereinbefore, is designated at O,and is slip-driven by a driver or prime mover P. A tuned elasticvibration transmitter or elastic resonator T is coupled to thisgenerator and to the work or load, designated generally at L. In thepreferred case, here diagrammed, the member T is coupled between thegenerator and the load, though broadly it is only necessary that theseelements all be acoustically intercoupled and the generator andresonator thus could be attached to the load at a common coupling point.The load L is to be understood to have an impedance which variesmaterially during the performance of the work, i.e. with consumption ofsonic energy, thereby modifying in an advantageous manner theperformance of the generator 0. It consists in this instance of twoelements to be welded, w and w, which are in frictional, vibrational,sliding contact, as represented, and one of which is on or positivelyattached to, or forms a part of, the vibration transmitter T, so as tobe directly vibrated by the vibrations transmitted to it and into it bythe latter. Thus, in one typical and common case, for example, thevibrations are transmitted elastically along the transmitter, and thenceinto and along or within the work piece connected to the transmitter.The entire system, composed of generator 0, vibration transmitter orresonator T, and load L, constitutes a discrete resonant acousticcircuit. Thus, the generator 0 is driven by the prime mover P at afrequency at which the circuit is in the range of resonance. To obtainimportant frequency stabilization benefits, the prime mover drives thegenerator at a frequency in the resonance range, but somewhat under thefrequency for peak resonance. Further, the prime mover for the generatoris matched in the acoustic circuit in such a manner that it will justsupply the drive torque necessary to establish and maintain operation ina resonant range but below the peak of resonance. As mentionedhereinabove, a slipdrive type of prime mover is capable of doing this,e.g., a fluid motor, with just enough torque to hold operation up to theresonance range, but insuflicient to obtain the peak of resonance. Also,an electric motor inversely speed-responsive to load, such as aninduction motor, or a series-wound motor, can carry out this function.The components 0, T and L of this discrete circuit all enterintrinsically into the resonance performance, and present a combinationof mass and elastic compliance reactances which cancel out internally ofthe acoustic circuit at its resonant operating frequency.

The vibration transmitter T may vibrate longitudinally, laterally,torsionally, or gyrationally (which is a special case of two lateralvibrations in quadrature). The oscillator is understood to be connectedproperly to the trans- 11 mitter to produce any desired one of suchmodes of vibration. The vibration transmitter is positively connectedto, or forms an integral part of, one of the work pieces, so that saidwork piece vibrates directly and in full accord with the portion of thetransmitter to which it is connected.

The load L has a frictional resistance factor R, owing to the workpieces w and w' vibrating against and relatively to one another, and inthe operation of the system, this factor R may hold constant for a time,and then as temperature rises by reason of the friction, and the metalof the parts softens, the frictional factor diminishes, and may finallydrop substantially to zero. In the meantime the parts w and w fuse andbecome forged or Welded to one another, so that the reactance of thepart w' is added to the system. Thus the impedance of the load changes,by diminishing friction R, often accompanied by increasing reactance.The diminishing friction, and also the increasing reactance, lead to areduced power factor, a higher Q, and a modified reasonance frequency(in some forms lowered, by addition predominantly of mass reactance). Tothese changes, the slip-driven orbiting mass oscillator instantlyresponds, continuing to deliver power at reasonance, preferably justunder the peak of resonance, and following any changes in resonancefrequency, always with the proper phase angle to sustain the loadthroughout the changing conditions of the process.

Following fusion of the parts, vibration is of course terminated, andthe parts are cooled, or allowed to cool.

In the work process represented in FIG. 1, the vibration transmitter Tis typically a longitudinally elastically vibratory bar, vibrating atresonance, in an effectively half-wavelength standing wave pattern(actually, somewhat shorter owing to lumped constant effects at the endof the bar). As the weld is made, the mass of the added work piece isadded onto the end of the bar and vibrates therewith. Typically, thisadds inductance or mass reactance, while frictional resistance isgreatly reduced, and the resonant frequency of the system accordinglylowers. The slip-driven orbital-mass generator follows this loweringresonance frequency, and changes its phase angle and power factor, asmentioned hereinabove. In this process, the changes referred to arefacilitated by an acoustic lever effect, by which the impedance of theload is matched or adjusted to the impedance of the generator by theintervening vibration transmitter bar. Thus, the ratio of cyclic forceto vibration amplitude at the generator is matched to a higher ratio ofcyclic force to vibration amplitude at the location of the weld,particularly after the weld has set up somewhat, and if the part weldedon is of large mass. In such case the amplitude of vibration in theelastic vibration bar is of course greater at the generator than at theweld. In any case in which this effect is not needed, the elasticvibration transmitter bar need not intervene between the generator andthe weld. Instead, by a mere reversal of parts, the generator may bedirectly connected to one of the work pieces to be welded, and theelastic bar then simply coupled to the generator. In such case, theelastic bar still plays an essential role, since it is a necessaryelement to the acoustic resonant circuit, and acts to afford the tuningto resonance and automatic resonant frequency accommodation essential tothe invention.

In this case, as mentioned, the progress of the work is accompanied by adecrease in resonant frequency, which is followed by the orbital-massgenerator. There are also cases in which changing character of the loadduring the work process results in an increase in resonant frequency,and as pointed out hereinafter, such a change will also be followed bythe orbital-mass vibration generator.

Reference is directed to FIGS. 2-8, inclusive, illustrative of anapplication of the invention to the welding of pipe joints, applicablewith particular efficacy and advantage to aluminum pipe. In thispractice of the invention,

the mode of sonic vibration may be a torsional mode, a gyrating mode, ora lateral mode. The illustrative machine disclosed herein showsparticularly a torsional mode. In the carrying out of the invention, anovel machine has been contrived which is characterized by bothcompactness and easy portability, and thus is adapted for use out in thefield where pipe lines are being laid.

A principal advantage of the sonic pipe welding process of the inventionis that it can accomplish fusion welding without causing residuallock-up stresses in the joint such as occurs with normal electric are orother conventional welding processes. Also, with the sonic process, itis possible to readily obtain a lead-proof joint, with a very closeapproach to one hundred percent of the strength of the original pipe.The process is applicable with alloys which are difficult to Weld byelectric or acetylene type Welding. Moreover, the use of sonic fusionwelding eliminates fire hazards accompanying electric or acetylenewelding of long pipe joints.

The sonic fusion pipe welding machine of the invention is designated byreference numeral 70, and is shown applied to the welding together ofthe ends of two pipes 71 and 72, of which the latter may be the end pipesection of a previously laid pipe line, and the former may be a new pipelength to be added.

The machine is shown to include a hanger yoke 74, suspended by a cable75 from any suitable means of support not shown. The hanger yoke 74 hastwo yoke arms in the form of spaced sleeves or collars 76 which receivea horizontal suspension pipe 77 projecting in opposite directionstherefrom, and the pipe 77 is secured to the hanger 74 as by welding.

On one side of hanger 74, the pipe 77 has welded thereto a dependingsuspension means 80 for a clamp means 81 for clamping tightly to thepipe 72. On the opposite side of hanger 74, a somewhat similarsuspension means 82 is provided, but is arranged for sliding movementalong the pipe 77, and this suspension means 82 carries a clamp means 83for the pipe 71, the clamp means 81 and 83 being similar to one another.

Rotatably mounted on the pipe 77 between collars 76 is a housingassembly 86 for an electric motor 87, to the shaft of which is coupled amilling cutter 88 adapted for engagement with the ends of both of pipes71 and 72 when the pipe 71 has its extremity substantially in theposition indicated in dot-dash lines 71a in FIG. 2. The housing assembly86 has fixed thereto a spur gear 90 surrounding and rotatable on thepipe 77, and meshing with this spur gear is a spur gear 91 on a shaft 92journaled in the lower end portion of a bracket arm 93 projecting fromhanger 74. On spur gear shaft 92 is fastened an operating lever 95. Whenthe milling cutter 88 has completed its operation of finishing off theends of pipes 71 and 72 (the pipe 71 being in position 71a, FIG. 2), thelever 95 may be swung to rotate the housing assembly 86, through gears91 and 90, so as to swing the milling cutter 88 to a position ofclearance relative to the pipes 71 and 72 (FIG. 3). The two pipe clampmeans 31 and 83 are similar, and will next be described. The lowerportion of the suspension means 80 or 82, as the case may be, comprisesa thick and massive plate member 100, affording the acoustic circuitmass element M (FIG. 7). Plate has a transverse tapered bore 101receiving, with clearance, the corresponding pipe member, as shown. Apair of arcuate wedge slips 102 are receivable in the tapered bore 101on opposite sides of the pipe, and when forced inwardly axially of thepipe, are wedged radially inwardly to clamp the pipe tightlytherebetween. The wedge slips 102 are so forced inwardly by hydraulicpressure exerted against pistons 104 connected to the slips by links 105and working in cylinders 106 mounted in the plate 100, all as clearlyshown in FIG. 2. Hydraulic fluid is introduced into the cylinders 106underneath the pistons to effect clamping action by fluid introducedunder 13 pressure via passageways 107, and may be exhausted from thespaces above the pistons via passageways 108.

As will be evident, the hanger plate members 100, which may thus be verytightly clamped to the pipes 71 and 72, are relatively massive, andthus, from the acoustic standpoint, mass-load the pipes at the clampingpoints. An inductive or inertial mass reactance is thus added to thepipe at a predetermined distance from the free extremity thereof, andthereby, as will be described in more particular hereinafter, a nodalpoint for the sonic standing wave set up in the pipe is established atthe clamping point.

A pipe alignment jig, generally designated at 110, is suspended by alink 111 from the arms 76 of the yoke 74 on the side of the fixedsuspension means 80, as illustrated, and this jig provides alignmentguide bushings surrounding the pipes 71 and 72 closely adjacent theopposed extremities of the latter, and affords mountings for componentsas presently to be described. The bushings 112 preferably comprisesuitable plastic rings 113, composed of a suitable material such as afiber-filled molded phenolic resin. The plastic rings 113 may be moldedinside cylindric casings 114. The latter are tightly received inside thehub portions 116 of jig frames 117, in which are tightly mounted,outside of and on opposite sides of the alignment bushing 112, a pair ofelectric drive motors 118, which may be induction motors, or preferably,in many case's, series-wound D-C motors having a substantial inversespeed-responsive characteristic to load. The motors 118 have driveshafts which are parallel with the pipes 71 and 72 and which driveorbital-mass type vibration generators or oscillators 120 of the generalcharacter heetofore described. These generators 120 may be, for example,of the type shown in FIG. 1 of my Pat. No. 3,217,551, to which referencemay be had for a thorough understanding. Suffice it to say that thegenerators 120, when driven by the motors 118, produce rotating forcevectors turning about the axes of the motor shafts, and exerted by thehousing of the generator on the structure that is supporting thishousing. In this case, the housing of each vibration generator 120 istightly received in the outer portion of a transverse frame 123, whichhas a central base portion 124 formed with a tapered bore 125 whichsurrounds, with clearance, the pipe 71 or 72, as the case may be, andwhich is clamped tightly to the pipe by wedge slips 126 inserted insidethe tapered bore 125 and forced tightly against the pipe by tightlysetting up holding screws threaded through the wedge slips and into thehubs 124. The frame affords, in effect, two radially oppositelyextending torque arms 127 clamped to the pipe. Thus, the rotating forcevector generated by each oscillator 120 is exerted on the free end ofthe corresponding torque arm, and is applied by said arm as anoscillatory torque on the portion of the pipe 71 or 72 clamped by thattorque arm.

It is to be noted that each of pipes 71 and 72 thus has clamped thereto,near its free end, through a pair of torque arms, a pair of orbital-massvibration generators. These are phased to coact torsionally in anadditive sense, as will be described more fully hereinafter. As oneoptional means for phasing the two pairs of vibration generators onopposite sides of the joint between the two pipes, I here show the motorshafts 130 and 131 to be provided with a slip coupling 132, which may beof any suitable type-for example, a splined shaft in a splined couplingsleeve, as here represented. The reason for this phasing will bereferred to more particularly in the ensuing discussion of operation.

To complete the description of the jig 110, the two jig frames 117 aresuitably interconnected with one another, as here shown. By being formedat the bottom with sleeves 136, one of which tightly receives aconnecting shaft 137, and the other of which slidably receives saidshaft. The frames 117 may thus move toward one another when the pipeends are moved together. The shaft 137 is shown to project from theouter extremities of the sleeve members 136, and to pass with clearancethrough apertures 138 formed at the bottom of the oscillator supportframes 123. In the operation of the device, the frames 123 oscillatetorsionally through a small angle, and the apertures 138 accommodatesuch torsional deflection. At the same time, the projection of the shaft137 through the apertures 138 in the oscillator frame 123 assures orfacilitates rough alignment of the parts.

Operation is as follows: The machine is assembled first with the pipe72, being positioned and clamped thereon as illustrated in FIG. 2. Thenew pipe length 71 to be added is then brought up, run through the clampmeans 83, vibration generator frame 123, the alignment bushing 112, andon up to a position such as illustrated at 71a in FIG. 2. It is thenclamped both by clamp means 83, and the torque arm wedge slips 126. Atthis time, the opposed end portions of the two pipes 71 and 72 willnormally be somewhat in the path of the motor driven milling cutter 88as the latter is swung in a plane transversely of the pipes by operationof lever 95. Thus the ends of the pipe are provided with nicely squaredend surfaces which, because of the alignment of the pipes assured by theguide bushings mounted on the jig, will come into good aligned abutmentand full-face engagement with one another when milling cutter 88 hassubsequently been swung aside and the pipe 71 advanced toward the right.It will of course be understood that the drive motor 87 drives themilling cutter 88, and that the swinging action of the milling cutterwhile rotation takes place is accomplished by swinging of theaforementioned lever 95. When the pipe and finishing operation has beencompleted, the milling cutter is swung out of the way by means of handle95, as to the position of FIG. 3, and the pipe 71 then moved to theright to engage the pipe 72, as shown in FIG. 2. This movement may beaccomplished by the hydraulic jack indicated generally at 139, pivotallyconnected at one end to the suspension means 82, as indicated at 140,and linked at the other end to an ear 141 formed on the adjacent arm ofthe yoke 74. The internal details of the hydraulic jack 1319 need not beshown, since hydraulic jacks are well known. However, as will beunderstood, admission of pressure fluid to the chamber of this jack willbe understood to actuate a plunger therein so as to slide the suspensionmeans toward the right on the pipe member 77 until the pipe 71 abuts thepipe 72. This hydraulic jack 139 can also be used to maintain a lightpressural contact of the two pipe ends against one another.

The torsional vibratory action induced in the pipes 71 and 72, and themanner of producing this vibratory action by the vibration generatorsdescribed hereinabove, will now be explained. Consider first theleft-hand pipe member 71. This pipe member is tightly clamped at acertain distance back from its free end by the relatively massiveclamping means 83. This point of the pipe, therefore, is substantiallyrigidly held, both by virtue of the clamping action, and by virtue alsoof the inertia or mass M of the relatively heavy clamping means appliedthereto. Accordingly, the oscillatory torque exerted on the pipe 71,applied to the pipe near the milled-off, free extremity thereof, causesthis portion of the pipe to elastically twist in first one direction andthen the other, with the amount of the twist progressively decreasingfrom the point of application of the oscillator torque to the pointrigidly held by the clamp means 83 and made steady by the mass M. Byproperly relating the length of the pipe between the clamp means 83 andthe free end of the pipe to the frequency of torsional oscillation, aquarter-wavelength, resonant standing wave pattern of a torsional modecan be set up in that portion of the pipe, there being a node N of thisstanding wave at the clamp means and mass M, and an antinode V of thestanding wave at the free extremity of the pipe. Those skilled in theacoustics art are familiar with this relationship. Similar torsionalresonant standing wave vibration or oscillation is set up in the pipe72, and reference is made to FIG. 7 for a diagrammatic representation ofthese actions. At Si is represented a quarter-wavelength torsionalstanding wave for the pipe 71 from the node to the antinode, andsimilarly at Si is represented the corresponding standing wave for thepipe 72. It is further a preferred feature of the invention that whenthe pipe 71 is twisting in one direction, the pipe 72 is twisting in theopposite direction, the purpose being to have maximized relative motionbetween the ends of the pipe, so that these will work frictionally onone another to a maximized extent and thus readily accomplish a fusionweld. It is of course not strictly necessary that the two pipes 71 and72 oscillate precisely 180 out of phase, though this is preferred as itaffords a maximum frictional action. However, the process can be carriedout just so that there is some frictional rubbing of one pipe end on theother as the two pipes undergo their torsional oscillation. Referringfurther to FIG. 7, it will of course be understood that the standingwave diagrams Si and Si represent the amplitude of torsional elasticdeflection in each of the pipes 71 and 72 between the nodes N and theantinodes V at different points along the pipe, the amplitudes, asshown, being maximized at the free extremities of the pipes.

Synchronization and phasing of the various generators is preferablyobtained in the following manner. Reference is directed to diagrammaticFIG. 8, showing the pipe 71, the two torsion arms 127 and the twovibration generators 120 mounted on the two torsion arms. Each vibrationgenerator involves an inertia mass rotor 150 rolling around a raceway151 in an orbital path, so as to apply to the raceway I15]. and thus tothe external housing of the vibration generator a rotating force vectorturning about the central axis Y of the raceway. It will now be observedthat if the orbital rotors I150 are phased at 180 opposition to oneanother, as represented to be in FIG. 7, the components of radiallydirected force in line with the torque arms 127 will always be equal andopposed and therefore cancel within the structure of the torque arms 127and the intervening pipe 71. Also, the components of force at rightangles to the arms 127 will always be equal and opposed, and thus willall cancel. However, these latter forces exert force couples, i.e.torsional deflecting forces, on the pipe, and it will be seen that theseare first in one direction and then the other as the rotors go aroundthe two opposite sides of the raceways. In summary, I thus apply to anend portion of each of the two pipes 71 and 72 an alternating forcecouple, such as elastically twists the two end portions of the two pipesalternately in reverse directions.

The aforementioned synchronization or phasing of the two orbital-massrotors 150 of each pair of oscillation generators on the same side ofthe pipe joint may be accomplished in various ways, such as by gearingtogether the two vibration generators, or by phasing properly the twodriving motors 118. Even without any such phasing, however, the twoorbital-mass rotors are found to selfsynchronize themselves entirelyautomatically when acting as component parts of a resonant vibratorysystem. This system was described in my aforementioned Pat. No.3,217,551. The synchronization or phasing of the two orbital-mass rotors150' of each pair of generators 120 is thus simply accomplished in anyof various ways.

As pointed out hereinabove, it is also preferable that the pairs ofgenerators 120 clamped to the two pipes 71 and 72 on opposite sides ofthe pipe joint operate in phase opposition, so as to assure oppositedirections of oscillatory twisting of the two pipe ends on one another.To this end, and for simple illustration, the shafts of the two lowermotors 118 have been coupled together by a coupling 132, and if thebacks of the motors on the opposite sides of the pipe joint to be madeshould of course have opposite normal directions of rotation. Of course,

if the four motors all face in the same direction, they can all have thesame normal direction of rotation. Assuming such an arrangement to havebeen made, the vibration generators directly driven by the two lowermotors can then be preliminarily phased in opposition, and each of theselower motors can then be arranged for provisions for phasing properlywith the motor above it, or will automatically phase with the motorabove it, in the manner heretofore described.

However, these phasing arrangements are carried out, the result is thatthe two ends of the two pipes 71 and 72 oscillate torsionally in lightcontact with one another. To accomplish proper performance in accordancewith the invention, each pipe end is at the velocity antinode of atorsional elastic resonant oscillation of a quarter-wavelength of thepipe, and this is accomplished by providing a proper length of pipe fromthe clamp means and mass M to the free extremity of the pipe such that aresonant, quarter-wavelength standing wave performance, in a torsionalmode, takes place in that length of pipe at the frequency established bythe drive motors 118. Under these circumstances, a large amplitude oftorsional vibration takes place at the two extremities of the two pipes,and thus the two pipes are frictionally rubbed on one another atsubstantial amplitude under a resonant performance. Of course, as inearlier described forms of the invention and in the introductory portionof this specification, it is to be understood that the motors 118 areactually given a normal performance characteristic such as to drivenormally at a speed or frequency which drives the vibration generatorsjust under the frequency for the peak of resonance; and, as alsodescribed hereinabove, the drives are preferably of a slip type and withsuch characteristics as to be inversely speed-responsive to load. Thesystem then operates with frequency stability, and with capability foraccommodating to changes in the impedance of the load, which in thiscase is the pair of pipe extremities vibrating torsionally against oneanother.

At the outset, the load will be seen to have a large energy dissipativefactor or resistance. As the fusion welding process goes forward, thisresistance is modified, and reactances are introduced, with consequencechange in the impedance of the load. Reference is again directed to FIG.7, showing at the top the two standing wave performances of the twopipes 71 and 72 prior to softening of the metal by the heat of frictionand thus prior to the beginning of fusion. As the two pipe ends heat up,they begin to soften and to fuse to one another.

Initially, frictional resistance between the pipe ends oscillatingagainst one another is high, meaning, of course, a high power factor forthe orbital-mass vibration generators. This resistance factor may or maynot increase as temperature first increases; but when the metal softensand begins to fuse, the frictional factor decreases, and each shaftexperiences the effect of reactance from the other to which it is thenpartially joined, so that there is a change in impedance. The phaseangle thus begins to increase and the power factor to decrease. Themotordriven orbital-mass vibration generator adjusts to these changes inload, as explained heretofore, thus maintaining good impedanceadjustment to the load. As the shaft ends progressively undergo fusionto one another, the wave pattern shifts from those of Si and Si throughthat represented at I, where the vibration amplitude is decreased,producing at the joint a sort of pseudonode Ni where the antinodes wereonce located to the final pattern at F, where there may be substantiallyor nearly a node Ni at the joint. There is then an antinode at Vf; andit will be seen that the wavelength of the pattern has then approachedhalf of what it was initially, while the frequency of the waveapproaches double its initial frequency. In other words, there is now aresonant frequency at double that at the beginning of operation; and themotor-driven vibration generators automatically follow this increase inresonance frequency. They do this because, as resonance frequencyincreases incremently, there is a momentary increment of decreased loadon the drive motors at the original frequency. The drive motors respondinstantly with increased speed. Also, the motors are again madeinsufficiently powerful to drive the system up to and over the peak ofresonance, and the system tends to stabilize just below peak resonance,as before. The system again therefore accommodates for changes inimpedance, and accommodates also for changes in resonance frequency asthe parts are joined.

Reference is next directed to FIGS. 9-11, showing an additionalapplication of the invention wherein a lateral mode of vibration isutilized to form a fusion weld between the ends of a tubular shaft and apair of universal joints.

A tubular shaft is designated generally by the reference numeral 160,and to the two ends of this shaft are to be fusion welded two universaljoints 161. As here shown, the butt end or root of each of theseuniversal joints includes a tubular member 162 receivable with a freefit inside the end portion of the shaft 160, and formed with a shoulder163 adapted to abut the end of the shaft 160. The weld is to be made onthe facing and abutting surfaces on the end of the pipe 160 and theshoulder 163.

The universal joint 161 is completed by two arms 164 supporting auniversal joint pin 165, and in the apparatus here shown, the universaljoint at one end is sup ported by an arcuate seat 166 engaging the pin165 and projecting from a suitable fixed support generally representedby the numeral 168. At the other end, the pin 165 is engaged by a seat166 which is on a plunger shaft 169 projecting from a hydraulic jack 170on a suitable fixed support 172. It will be understood that the plungershaft 169 has inside cylinder 170 a plunger head working in acylindrical chamber, and that suitable hydraulic lines are provided,together with suitable controls, whereby the plunger 169 may be extendedor retracted to engage and support a universal joint assembly such asdescribed, or release it when the work has been finished.

The present application of the invention involves the use of a lateralmode of resonant elastic vibratory action in the hollow shaft 160, witha wave pattern such as represented in the diagram of FIG. 12. Toaccomplish the wave pattern as represented, I mount on the centralregion of the shaft 160 an orbital-mass vibration generator of the typeheretofore described, and as indicated in the drawings by the referencecharacter 175. The generator 175 delivers to its exterior housing 176 arotating force vector, turning about an axis X-X'. The housing 176 willbe seen from FIG. to have an arcuate seat 177 which engages the lowerside of the shaft 160, while the upper side of said shaft, just aboveseat 17 7, is engaged by an arcuate seat 178 on a pad or head 179 on thelower end of a plunger 180 extending from a hydraulic jack 181. Thehydraulic jack 181 and the body plate 182 in which the aforementionedseat 177 is formed, are connected by tie rods 183, and thus extension ofplunger 180 and clamping head 179 under hydraulic control of pressurefluid delivered to the hydraulic jack 181 affords a tight clampingengagement of the generator 175 to the center portion of the shaft 160.

In the simple form here shown, the generator housing 176 has,concentrically located with the transverse axis X-X', a bore 184containing a raceway cylinder 185, the latter having formed therein arecessed, cylindrically formed raceway surface 186 for an inertia roller187. The latter is driven to run around the raceway surface 186 by meansof air under pressure supplied via an air hose 188 and leading to a jetor nozzle passageway in the body 176 and the raceway member 185 to opentangentially inside the raceway surface 186. Air under pressuredelivered from this tangential nozzle drives the rotor 187 to spin aboutthe raceway surface 186. This will be seen to be a slip-drive type ofvibration generator as referred to hereinabove. The cylindrical rotor187 rolling around the inside of the raceway surface 186 generateswithin the raceway member 185, and thus within the housing 176 holdingthe latter, a radial force vector turning about the axis X-X, aspreviously mentioned.

It is to be understood that the pressure and volume of air delivered viathe hose 188 must be such as to drive the generator rotor 185 at afrequency approximating, but preferably on the low side of, the resonantfrequency for a mode of lateral standing wave vibration, preferably thefull-wave length mode as diagrammed at Si in FIG. 17. Under theseconditions, as represented in this diagram, there is a velocity antinodeV, or region of maximized vibration amplitude, at each end of the shaft,as well as a velocity antinode V at the center, while there are nodes N,or regions of minimized vibration amplitude, at points approximately 20%of the length of the shaft from each end, as represented. The vibrationin the shaft will be seen to take place, because of resonance in thelateral node, in planes transversely of the shaft, but it will beevident that the vibration generator will also deliver to the pipe 160 acomponent of alternating force disposed longitudinally of the pipe. Bydriving the generator at the frequency for resonance in the lateralmode, or preferably, as heretofore explained, just below the frequencyfor lateral resonance at peak amplitude, the normal blocking impedancefor vibration in the transverse mode is greatly reduced, so that largeamplitudes of vibration may be experienced at the antinodes intransverse planes (in this case, vertically). On the other hand, thecomponents of vibratory force exerted by the generator 175 in directionslongitudinal of the shaft 160 are not near to any longitudinal resonantfrequency of the shaft, and therefore longitudinal components ofvibration in the shaft 160 are of small magnitude and can be neglected.

Thus, in the operation of the system, the two opposite end portions ofthe shaft 160 are vibrated in transverse planes, i.e. in the plane ofthe two end surfaces of the shaft, at a resonant frequency of the shaftfor the transverse resonant standing wave mode employed. The two ends ofthe pipe thus vibrate transversely against the universal joint shoulders163. It will be evident, of course, that the vibratory amplitudes of theend portions of the shaft 160 are relatively small. They are, however,very powerful. The universal joint, on the other hand, is not tightlyenough joined to the shaft 160, prior to welding, that it will be causedby frictional forces to follow the vibratory action of the shaft.Accordingly, the type of sonic vibratory action, at a resonant frequencyof the system, causes relative vibration of the parts, and thereforefrictional heating, until the metal melts and fuses. In thisperformance, changes of impedance take place, analogous to thosedescribed in earlier embodiments of the invention, and in theintroductory portion of the specification, and the orbital-massvibration generator 175 automatically accommodates for these changes,all as heretofore described.

Reference is next directed to FIGS. 13 and 14, showing a finalapplication of the invention, in this case to the fusion welding of ashaft or pin to a surface of a body, in this case using a gyratoryand/or torsional type of resonant elastic standing wave vibration in theshaft.

The shaft, which must be of an elastic material, such as steel, or aresin, is designated generally at 190, and as here shown, has anenlarged head 191 on one end thereof. This head 191 is shown to abutagainst a surface of a body 192, positioned by an abutment 193 securedto the work table, as illustrated. The other end of the shaft isreceived, with clearance, in a socket 194 formed in cup 195, and engagedby a coil compression spring 196 in the bottom of said cup. The cup isslidable in a bore 197 in a support 197', and is connected via a link198 with the short arm 199 of a clamp lever 200 pivotally mounted at 201on a mounting bracket 202. The lever arm 199 and the link 198 form atoggle, enabling the parts to be positioned by 19 handle 200 so that theleft-hand extremity of the shaft 190 is under spring pressure from thespring 196 during operation, whereby the head 191 on the opposite end ofthe shaft 190 is lightly pressed against the body 192 to which it is tobe welded.

In this application of the invention, a gyratory (or torsional) type ofresonant standing wave is set up on the pipe 190, and for this purpose,a vibration generator 205 is clamped to a center region of the shaft190. The generator 205 may be the same as the generator 175 of theembodiment of FIGS. 9-11, but with the exception that the axis of therace ring for the orbital-mass rotor, here designated at 206, and itscylindrical raceway 207, have been turned through 90, so that the axesthereof are parallel with the shaft 190. The orbital-mass rotor 208 actsto generate and apply to the generator housing, and thence to the shaftto which the generator housing is clamped, a rotating force vector,which rotates about a longitudinal axis near and parallel to the shaft.The elastic shaft is thereby set into a bodily gyratory type of motion,which actually amounts to two rectilinear vibrations on axes at rightangles to one another and occurring with 90 phase differencetherebetween. This motion is propagated along the length of the shaft,reflected from the ends thereof, and when the generator frequency iscorrect for resonance, a gyratory type of one-wavelength resonantstanding wave vibration takes place in the shaft. This type ofperformance was fully described in my aforementioned prior Pat. No.2,960,314, FIGS. 1-4, and the portion of the specification pertainingthereto. In this type of gyratory action, the end surface of the shaft190, or in this case, of the enlarged head thereon, gyrates bodily atthe resonance frequency in contact with the surface of the body 192, andthus friction is set up suificiently to heat and melt the metal in theregion of the two engaging surfaces, such that these surfaces fuse toone another.

As in the applications of the invention discussed hereinabove, theorbital-mass vibration generator slip-driven by pressurized fluid, againpresents the advantages of frequency stabilization, accommodation tochanges of impedance, in either or both of the resistive and reactivecomponents thereof, during changing conditions of the work process,automatic adjustment always to required phase angle and power factor, aswell as to any changes in the frequency for resonance, all as discussedhereinbefore.

It will be understood that the acoustic circuit of the invention,diagrammed in FIG. 1, is present in all of the disclosed illustrativeapplications of the invention. It should also be evident that thisacoustic circuit has a breadth of application going beyond that offusion welding, and extending to any process wherein impedance andfrequency changes may be encountered during a work process and wheremaximum performance demands automatic accommodation to these changingfactors.

I claim: 1. A sonic machine for fusion-welding the end of an elongatedelastic member, such as a pipe or the like, to another member inend-to-end engagement, that comprises:

means for supporting the members in end-to-end engagement, including amass loaded clamp means engagea'ble with one of the members at apredetermined distance from the engaged end of said member;

oscillatory torque generating means clamped to said last mentionedmember at a location towards the engaged end of the member from saidclamp means for setting up a torsional resonant standing wave in saidmember between said clamp means and the engaged end of said member; and

means for driving said oscillatory torque generating means.

2. A sonic machine for fusion-welding the end of an elongated elasticmember, such as a pipe or the like, to another member in end-to-endengagement, that comprises:

means for supporting the members in end-to-end en gagement, including aclamp means engageable with one of the members at a predetermineddistance from the engaged end of said member;

oscillatory torque generating means clamped to said last mentionedmember at a location towards the engaged end of the member from saidclamp means for setting up a torsional resonant standing wave in saidmember between said clamp means and the engaged end of said member, saidoscillator torque generating means comprising an orbital mass oscillatorhaving a housing containing a cylindrical raceway with an orbital massrotor running on said raceway;

and a torque arm fixed on said member and tightly supporting saidhousing to one side of said member, with the axis of said racewayparallel with the memher.

3. The subject matter of claim 1 wherein the engaged end of said memberis located substantially at an antinode of said standing wave.

4. The subject matter of claim 1, including:

a clamp means for each of said members;

a supporting means for said clamp means; and

means for moving at least one of said clamp means on said supportingmeans in a direction parallel to said elongated members clamped by saidclamp means.

5. A sonic machine for fusion-welding the end of an elongated elasticmember, such as a pipe or the like, to another member in end-to-endengagement, that comprises:

means for supporting the members in end-to-end engagement, including aclamp means engageable with each of the members at a predetermineddistance from the engaged ends of said members, supporting means forsaid clamp means, and means for moving at least one of said clamp meanson said supporting means in a direction parallel to said elongatedmembers clamped by said clamp means;

separate oscillator torque generating means clamped to each of saidmembers at locations towards the engaged ends of the members from saidclamp means for setting up torsional resonant standing waves in saidmembers between said clamp means and the engaged ends of said members;

means for driving said oscillator torque generating means; and

means maintaining a phase difference between the torsional standingwaves set up in the members whereby said members oscillate relatively toone another.

6. The subject matter of claim 5 wherein the phase difference maintainedbetween the torsional standing waves set up in said members issubstantially References Cited UNITED STATES PATENTS 10/1961 Tramm et al156-73 6/1971 Bodine 228-4 U.S. Cl. X.R.

